表面活性剂对均相沉淀法制备单晶Ce2O(CO3)2￠H2O微粉形貌及 形成机理的影响

在尿素及硝酸铈的混合溶液中分别加入表面活性剂CTAB、 PEG19000、OP-10,利用均相沉淀法合成了不同形貌的CeO2超细前驱体Ce2O(COa)2·H2O,采用X射线衍射及透射电子显微镜等测试手段,对产品的物相和形貌进行了表征．实验结果表明,所得产品均为斜方晶系的单晶Ce2O(CO3)2·H2O,且表面活性剂的加入使晶体的晶化程度明显提高;添加不同的表面活性剂得到不同形貌尺寸的产物: 阳离子型表面活性剂CTAB对Ce2O(CO3)2·H2O晶体的形貌影响不大,所得产物尺寸变小,且分散性得到一定的改善;非离子型表面活性剂对所得产物的形貌影响显著．加入PEG19000和OP-10分别得到了形状排列有序的、尺寸较均匀的、较规则无团聚的微米棒及具有紧密结合中心的发散状的花样微粒．不同形貌前驱体的形成与晶粒形成生长机理的改变有关．     

Influence of Self-Absorption and Impurities on Scintillation Properties of （Lu0.1Y0.9）A103：Ce Single Crystals

Lu0.1Y0.9AlO3：Ce single crystals in dimensions Φ30×90 mma are successfully grown by the Czochralski method. The light output and energy resolution of the crystal in dimensions Φ14×2mm^3 are 9420 photons/MeV and 12.5% respectively. Dependence of the light output on the thickness of the sample is found and explained by the self-absorption in the range of 320-370nm and the underlying parasitic absorption around 250hm. In addition, the local enrichment of Ce ions and the presence of low-valent impurity ions may cause the deterioration of its light output. In addition, Lu0.1 Y0.9AlO3：Ce has an almost constant fluorescence decay time of 16ns in the temperature range of 80-373 K.     

铕吡啶羧酸配合物[Eu（C7H3O4N）（CH3COO）（H2O）]·2H2O的合成、表征及其结构

在水热条件下,以2,5-吡啶二甲酸为配体合成得到稀土Eu^3＋为中心离子的配位聚合物[Eu（C7H3O4N）（CH3COO）（H2O）]·2H2O。用元素分析、红外光谱、单晶衍射对配合物的组成和结构进行了表征。晶体结构测试表明,标题配合物属于单斜晶系,空间群为P2（1）/c。在晶体结构中,构筑单位是含有Eu-Eu金属键的双核重复单元,六分子的吡啶二甲酸配体均以五齿配位的形式桥连4个Eu^3＋离子,从而将邻近的双核单元连接起来形成三维结构。     

稀土配合物Tb（Sal）3·3H2O纳米微晶的制备及发光性质

利用化学沉淀法制备了不同粒径的Tb（Sal）3·3H2O纳米微晶和Tb（sal）3·2H2O稀土配合物。利用元素分析、红外光谱、热重分析和透射电镜表征了纳米微晶和稀土配合物的结构、热性质和粒径大小。利用荧光激发和发射光谱、紫外光谱探讨了有机配体和中心离子之间的能量传递过程。结果显示Tb（Sal）,·3H2O纳米微晶的粒径主要分布在50～250nm区域并且发出较强铽（Ⅲ）离子的特征荧光。这些结果为进一步扩展稀土配合物在发光材料以及磁材料中的应用奠定了基础。     

Optical Dispersion Behavior and Band Gap Energy of Relaxor Ferroelectric 0.92Pb（Mgl/3Nb2/3）O3-0.08PbTiO3 Single Crystal

Refractive indices and extinction coefficients of O.92Pb（Mgl/3Nb2/3）O3-O.O8PbTiO~（PMN-O.OSPT） single crystaJ are investigated by variable angle spectroscopic ellipsometry （VASE） at different wavelengths. The parameters relative to the energy band structure are obtained by fitting to the single-oscillator dispersion equation, and the band gap energy is also deduced from the Tauc equation. Similar to most oxygen-octahedra ferroelectries, PMN-O.OSPT has the same dispersion behavior described by the refractive-index dispersion parameters.     

Effect of the O2/Ar Pressure Ratio on the Microstructure and Surface Morphology of Epi-MgO/IBAD-MgO Templates for GdBa2Cu3O7？δ Coated Conductors

High-quality epi-MgO buffer layers under different O2/Ar pressure ratios are fabricated by rf magnetron sputtering on textured IBAD-MgO templates. Under the total deposition pressure remaining constant （14 Pa）, the effect of changing the ratio of O2/Ar pressure from 1：4 to 3：2 on the microstructure and surface morphology of epi-MgO films is studied. The microstructure and morphology of epi-MgO are fully characterized by x-ray diffraction, atom force microscope and scanning electron microscope. The best texture quality of epi-MgO with an out-plane Δω value of 1.8° and an in-plane Δ？ value of 5.22° are obtained under the ratio of O2/Ar pressure 3：2. Further, the surface morphology indicates that the surface of epi-MgO is smooth with rms surface roughness about 4.7 nm at O2/Ar pressure ratio 3：2. After that, GdBa2Cu3O7？δ （GBCO） layers are deposited on the CeO2 cap layer buffered epi-MgO/IBAD-MgO templates to assess the efficiency of such a buffer layer stack. The critical current density of GBCO films （thickness of 200 nm） is higher than 3 MA/cm2, indicating that epi-MgO/IBAD-MgO is promising for depositing superconducting layers with a higher critical current density.     

A density functional theory study on the adsorption of CO and O2 on Cu-terminated Cu2O （111） surface

The adsorptions of CO and 02 molecules individually on the stoichiometric Cu-terminatcd Cu20 （111） surface are investigated by first-principles calculations on the basis of the density functional theory. The calculated results indicate that the CO molecule preferably coordinates to the Cu2 site through its C atom with an adsorption energy of-1.69 eV, whereas the 02 molecule is most stably adsorbed in a tilt type with one O atom coordinating to the Cu2 site and the other O atom coordinating to the Cul site, and has an adsorption energy of -1.97 eV. From the analysis of density of states, it is observed that Cu 3d transfers electrons to 2π orbital of the CO molecule and the highest occupied 5σ orbital of the CO molecule transfers electrons to the substrate. The sharp band of Cu 4s is delocalized when compared to that before the CO molecule adsorption, and overlaps substantially with bands of the adsorbed CO molecule. There is a broadening of the 2π orbital of the 02 molecule because of its overlapping with the Cu 3d orbital, indicating that strong 3d-2π interactions are involved in the chemisorption of the 02 molecule on the surface.     

{H[Cu（trans-Hcydta）]·2Bzim·1．5H2O·0．5MeOH·HClO4}的合成、结构和量子化学研究

反式．1，2-环已二胺四乙酸与铜离子合成标题配合物，经X射线衍射测定配合物的晶体分子结构，并用量子化学方法研究配合物的电子结构及分子轨道组成、该晶体属于单斜晶系，空间群为P2(1)／c，晶胞参数：a=1．6360(6)，b=1．3814(5)，c=1．5503(5)nm，β=90．885(7)°，V=3．503(2)nm^3，Z=4，Dx=1．495g／cm^3，u(MoKa)=7、74cm^-1，F(000)=1640，R1=0．0750，wR=0.1526；配合物中Cu-O键长为0．193～0．22nm，中心铜与配基原子形成畸型四棱锥。     

Resonant tunnelling of the magnetization in molecular crystal of [（Mn1-xCrx）12O12 （CH3COO）16（H2O）4]·2CH3COOH·4H2O（x=0,0.03,0.04,0.05）

The quantum tunnelling of magnetization （QTM） in single crystals of the single molecule magnet （Mn1-xCrx）12- Ac （x=0, 0.03, 0.04, 0.05） has been investigated. In comparison with its parent Mnl2-Ac, a greater rate of magnetization relaxation and a lower effective potential-energy barrier have been observed in Cr-doping samples. This modulation of QTM due to the Cr-doping could be attributed to the small change of Sz due to the smaller spin of Cr itself and additional intrinsic but distributed transverse and longitudinal anisotropy raised by a subtle change of the local environment in the magnetic Mn12 core.     

配合物[Zn（DMF）2（H2O）4]·C8Cl4O4的合成及其结构的研究

采用溶剂挥发扩散法合成了配合物单晶[Zn（DMF）2（H2O）4]·C8Cl4O4,其中DMF为N,N′-二甲基甲酰胺。配合物为三斜晶系,P-1空间群,其晶胞参数为n=0．57680（10）nm．6=0．85991（14）nm,c=1．2030（2）nm,α=95．781（3）°,β=102．074（3）°,γ：98．594（2）°,V=0．57154nm^3,Z=1,Mr=585．51,Dc=1．701g／cm^3,F（000）=298,μ=1．594mm^-1,最终偏差因子R1=0．0315,ωR2=0．0914．和R1=0．0345,ωR2=0．0946,同时采用红外光谱分析、元素分析对其进行表征。     

First-Principle Study of H2 Adsorption on Mg3N2（ll0） Surface

The adsorption of H2 on two kinds of Mg3N2（110） crystal surface is studied by first principles. Adsorption sites, adsorption energy, and the electronic structure of the Mg3N2（110）/H2 systems are calculated separately. It is found that H2 is mainly adsorbed as chemical adsorption, on these sites the 1-12 molecules are dissociated and the H atoms tend to the top of two N, respectively, forming two NH, or the H atoms tend to the same N forming one NH2. There are also some physicM adsorption sites. One of the bridge sites of Mg3N2 （110） surface is more favorable than the other sites. On this site, H atoms tend to the top of two N, forming two NH. This process belongs to strong chemical adsorption. The interaction between 1-12 molecule and Mg3N2（110） surface is mainly due to the overlap-hybridization among Hls, N 2s, and N 2p states, covalent bonds are formed between the N and H atoms.     

Orientation effects on the bandgap and dispersion behavior of 0.91Pb（Zn_（1/3）Nb_（2/3））O_3-0.09PbTiO_3 single crystals

0.91Pb(Zn_1/3Nb_2/3)O₃--0.09PbTiO₃ (PZN--9%PT) single crystals with different orientations are investigated by using a spectroscopic ellipsometer, and the refractive indices and the extinction coefficients are obtained. The Sellmeier dispersion equations for the refractive indices are obtained by the least square fitting, which can be used to calculate the refractive indices in a low absorption wavelength range. Average Sellmeier oscillator parameters E_o, $\lambda$_o, S_o, and E_d are calculated by fitting with the single-term oscillator equation, which are related directly to the electronic energy band structure. The optical energy bandgaps are obtained from the absorption coefficient spectra. Our results show that the optical properties of [001] and [111] poled crystals are very similar, but quite different from those of the [011] poled crystal.     

Guided Wave Propagation in a Gold Electrode Film on a Pb（Mg1/aNb2/a）Oa-33%PbTiO3 Ferroelectric Single Crystal Substrate

Dispersion relations of Love mode acoustic guided 0.33 PT） single crystal with a gold electrode film waves propagation in Pb（Mg1/3 Nb2/3 ） 03-33%PbTiO3 （PMN- are calculated. There is no cross coupling among Love wave modes, which is conducive to eliminating the cross interference between modes. The general formula is derived to precisely measure the thickness of the electrode. More acoustic energy would be concentrated inside the electrode with the increase of film thickness for a given frequency. Compared with the PZT-5 ceramic, [001]c poled PMN- 33%PT single crystal has a slower attenuation of the amplitude of the acoustic guided wave. Therefore, single crystal is extremely suitable for making low loss acoustic wave devices with a high operating frequency.     

A density functional theory study on the adsorption of CO and O₂ on Cu-terminated Cu₂O（111） surface

The adsorptions of CO and O2 molecules individually on the stoichiometric Cu-terminated Cu2O(111) surface are investigated by first-principles calculations on the basis of the density functional theory.The calculated results indicate that the CO molecule preferably coordinates to the Cu2 site through its C atom with an adsorption energy of -1.69 eV,whereas the O2 molecule is most stably adsorbed in a tilt type with one O atom coordinating to the Cu2 site and the other O atom coordinating to the Cu1 site,and has an adsorption energy of -1.97 eV.From the analysis of density of states,it is observed that Cu 3d transfers electrons to 2π orbital of the CO molecule and the highest occupied 5σ orbital of the CO molecule transfers electrons to the substrate.The sharp band of Cu 4s is delocalized when compared to that before the CO molecule adsorption,and overlaps substantially with bands of the adsorbed CO molecule.There is a broadening of the 2π orbital of the O2 molecule because of its overlapping with the Cu 3d orbital,indicating that strong 3d-2π interactions are involved in the chemisorption of the O2 molecule on the surface.     

High sensitivity gravimetric sensor made of unidirectional carbon fiber epoxy composite on （1 -- x）Pb（Znl/3Nb2/3）O3-xPbTiO3 single crystal substrate

We have derived a general formula for sensitivity optimization of gravimetric sensors and have used it to design a high sensitivity gravimetric sensor using unidirectional carbon fiber epoxy composite （CFEC） waveguide layer on （1 -x）Pb（Znl/3Nbz/3）O3-xPbTiO3 （PZN-xPT） single crystal substrate with the carbon fibers parallel to the xj and x2 axes, respectively. The normalized maximum sensitivity （｜sfm｜λ）max exhibits an increasing tendency with the decrease of （h/λ）opt and the maximum sensitivity （｜sfm｜λ）max increases with the elastic constant c6E6 of the piezoelectric substrate material. For the CFEC/[011]c poled PZN-7%PT single crystal sensor configuration, with the carbon fibers parallel to the xa axis at λ = 24 ktm, the maximum sensitivity ｜sfm｜max can reach as high as 1156 cmZ/g, which is about three times that of a traditional SiO2/ST quartz structure gravimetric sensor. The better design selection is to have the carbon fibers parallel to the direction of propagation of Love wave in order to obtain the best sensitivity.     

First Principles Study of Adsorption and Reaction of CO on SrTiO3 （100） Surface： the Role of Surface Oxygen Vacancies

The adsorption and reaction of CO on SrTiO3 （100） surface with and without surface oxygen vacancy are investigated by the first-principles calculation based on the density functional theory. The calculated results reveal that the oxygen vacancy site prefers to the activation of the C-O bond. The adsorption energies increase to 1.0855 and 0.3245eV for defect-CO and defect-OC orientations, respectively. Particularly the C-O bond is elongated by about 0.1285 ？ in the defect-OC orientation compared with that in the Ti-OC one without surface oxygen vacancies. There is predominantly a chemisorption mechanism between the CO molecule and the surface in the defect-CO orientation.     

Atomic Layer Deposition of Al2O3 on H-Passivated GeSi： Initial Surface Reaction Pathways with H/GeSi（100）-2 × 1

The reaction mechanisms of Al（CH3 ）3 （TMA） adsorption on H-passivated GeSi（100）-2 × 1 surface are investigated with density functional theory. The Si-Ge and Ge-Ge one-dimer cluster models are employed to represent the GeSi（100）-2 × 1 surface with different Ge compositions. For a Si-Ge dimer of a H-passivated SiGe surface, TMA adsorption on both Si-H^＊ and Ge-H^＊ sites is considered. The activation barrier of TMA with the Si-H^＊ site （1.2eV） is higher than that of TMA with the Ge-H^＊ site （0.91 eV）, which indicates that the reaction proceeds more slowly on the Si-H^＊ site than on the Ge-H^＊ site. In addition, adsorption of TMA is more energetically favorable on the Ge-Ge dimer than on the Si-Ge dimer of H-passivated SiGe.